Off-road vehicles are generally equipped with disk and friction pad type brake systems to provide braking to the off-road vehicle. U.S. Pat. No. 6,883,630 which is incorporated herein by reference discloses front disk brake assemblies mounted on the left and right coupling members of the universal joint extending on the left and right side of the front differential each of which are connected to the respective left and right half shafts transmitting power from the front differential to the front wheels. The left and right brake calipers are rigidly mounted to the housing structure of the front differential. The rear brake system disclosed in U.S. Pat. No. 6,883,630 consists of a single disk brake assembly mounted to the yoke of the universal joint at the front of the rear angle drive connecting the drive shaft extending from the engine to the rear angle drive. The single disk brake therefore rotates with the drive shaft while the rear brake caliper is rigidly mounted to the housing structure of the rear angle drive.
While this system works well and provides sufficient braking under dry and wet conditions, there are conditions such as when the off-road vehicle is going through water or a wet marsh where the friction between the brake pads and the brake disk is reduced and thus the braking force is also reduced. There are other instances where the brake disks may become covered with mud or other dirt and thus the braking force would also be reduced.
The rear drive train of a conventional off-road vehicle has a solid drive shaft connected between the engine and the rear angle drive assembly. The drive shaft transfers the torque from the engine transmission to the left and right rear half shafts to rotate the wheels and provide motive force to the rear wheels. Torque is delivered un-interrupted from the engine to the wheels. In some cases, when the wheels of the off-road vehicle are lifted off the ground, such as when the off-road vehicle jumps over bumps while torque is still being transferred to the wheels from the engine, a very high torque is generated in the drive train components when the wheels are suddenly brought back into contact with the ground under the weight of the vehicle. To prevent failure, the components of the drive train must be sized accordingly and thus are bigger/heavier and more costly than would be if they had to be designed only to deal with engine torque.
To reduce component size while maintaining durability and preventing failure, slip clutches are placed within the drive train. A slip clutch is a series of alternating drive and driven discs which are forced into contact with each other by spring mechanisms such as Belleville washers or a series of standard coil springs. The drive discs are connected to the upstream side of the drive line and the driven discs are connected to the downstream side of the drive line. Torque must pass through the drive and driven discs in order to go from the engine to the wheels and vice versa. The amount of torque which the slip clutch can transmit, without slip between the drive and driven discs, is determined by the force applied to the discs stack by spring mechanism. The force required by the spring mechanism is determined by the maximum torque to be resisted by the components of the drive train. Any torque higher than the maximum torque will cause slip within the slip clutch which will protect the drive train components.
Thus, there is a need for an off-road vehicle having a compact driveline that alleviates some of the drawbacks of conventional drive trains and braking systems of off-road vehicles.